Assessing Net Ecosystem Exchange of Carbon Dioxide Between the Terrestrial Biosphere and the Atmosphere Using Fluxnet Observations and Remote Sensing


The quantification of net ecosystem exchange (NEE) of carbon dioxide over regions, continents, or the globe is essential for understanding the feedbacks between the terrestrial biosphere and the atmosphere in the context of global climate change. The eddy covariance technique provides continuous NEE measurements for a variety of ecosystem and climate types. These measurements, however, only represent the fluxes at the scale of the tower footprint. Here a data-driven approach and satellite remote sensing are used to upscale NEE observations from eddy covariance flux towers to the continental scale and to produce gridded flux estimates for the conterminous U.S. over the period 2000–2009. The resulting 10-year gridded flux estimates (EC-MOD) have 1 km spatial resolution and 8-day time step, and provide independent and alternative NEE estimates compared to traditional approaches. These flux estimates are used to examine the spatial and temporal dynamics of NEE at seasonal, annual, and interannual scales. On average, the annual NEE of U.S. natural ecosystems is −0.54 Pg C year−1. The EC-MOD estimate of the U.S. carbon sink agrees with recent estimates from the literature. The dominant sources of the interannual variability in NEE of the U.S. include drought and disturbances. EC-MOD is also valuable for evaluating simulations from ecosystem models and atmospheric inversions.


Earth Systems Research Center

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Journal Title

Biophysical Applications of Satellite Remote Sensing



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Book Chapter


© Springer-Verlag Berlin Heidelberg 2014